This invention relates to a method of manufacturing a camera tube faceplate and more particularly to one in which a conductor is incorporated in the faceplate.
Camera tubes generally have a glass faceplate on which is deposited an electrically conducting transparent layer called the signal plate. A photosensitive layer is deposited on the signal plate and forms what is known as the target. In operation a current passes into the signal plate having a value which is dependent on the level of illumination of part of an object being scanned at that time. This current is conventionally conducted out through the outside edge of the signal plate.
It is desirable that the electrical capacity of the signal plate be low to give increased sensitivity. This may be achieved by reducing the area of the signal plate and, instead of taking the current from the edge of the signal plate, by transmitting the current along a conductor located as close as possible to the screen without it encroaching on the image area. However, previous methods of embedding a conductor in the glass faceplate to give this advantage have proved unsatisfactory, being difficult to carry out, introducing distortions and giving incomplete fusion of glass at joints between different sections and at the conductor.